President Joe Biden said during a Dec. 11 phone call with Ukrainian President Volodymyr Zelenskiy that strengthening Ukraine's air defense is a priority in providing defense assistance, the White House said in a released statement.

Biden welcomed the Ukrainian president's commitment to a just peace based on the fundamental principles enshrined in the UN Charter.

Zelenskiy said that, during his conversation with President Biden, he thanked him for the "unprecedented" assistance provided to Ukraine after the February 2022 invasion by Russian troops.

"I was glad to feel in the conversation that our peace formula was perceived positively. And this adds optimism. The sooner the points of the formula are implemented, the stronger the security guarantees of Ukraine and everyone in Europe will be," Zelenskiy told Biden.